How to restore the classic Youtube interface

In classic large-company fashion, Youtube have managed to totally fuck up their latest no-reason-just-because interface "refresh" into bloatware.  From something that was clean, minimalist and informative it's now a "metro" mess of iconic rubbish that looks like Fisher-Price designed it.

No worries, just click the link to go back to the Classic interface, right?  Wrong, the pricks have removed that too.

To fix this (in Chrome) -

Start in a tab with Youtube open

Hit Ctrl+Shift+I to open the Developer Tools pane.

Change to the Applications tab inside that pane.

Find "Cookies" in the left hand menu and select the Youtube entry.

In the main table, find the row for "PREF" and edit the Value field to:  al=en&f5=30030&f6=8

Close the Developer Tools pane and refresh and you should be back to Classic.

Note this is a per-browser setting, not linked to your account, so you have to hack each PC you use.